2,051 views

29 secs S

Watch
- Search Videos
  
  Advanced search »
- Submit a New Video
Discuss
About
- Try clicking on the various channels to see videos posted to that channel - if you're into music you can click the Music channel to get more music sifts - go on and explore! Use the "hotness" when you have opened the channel link to get videos that have gotten a lot of votes, or use "newness" to have a look at the new sifts.
  When browsing sifts you like, have a look at the Related Posts list to see other related videos, click the tags under the video title to see more sifts tagged with the same tags or have a look at other sifts from the same user in the More Posts By list. If the sifted video is in a play list, have a look at the play list to see other interesting videos the Sift users have linked together.
  Enter the Sift Lounge to chat with online sifters about anything and everything, or read interesting posts in the Sift Talk forum.
  The Top New Videos list is always full of interesting, current videos. It is always recommended that you have a look through the Top New Videos, but also have a look at these:
  - Upcoming Unsifted Videos - active video submissions that neither are published to the front page nor archived to the submitter's personal queue
- Have you seen a really funny, surprising, scary, interesting, cute or in any other way extra good quality video?
  Post and share it here - VideoSift is the best video aggregator on the Web, where we share, discuss, promote, and interact with the best videos out there on the web. Post it here, and share it with the large community of video-interested users. And - you are guaranteed to find more very good videos here already!
  Mind you, we only share videos you discover that someone else has made; if you "self link," by posting a video you have made, have posted or have interests in, you risk the ban hammer - read the posting guidelines before posting. The sift is NOT for promoting your own videos - it is for sharing videos others have made.
  Submit a Video Now »
Login

Orange LED in liquid nitrogen

submitted by mintbbb

1 decade 1 year 1 month 2 weeks ago

Science

YouTube Description:

We submerge an orange LED into liquid nitrogen which causes the LED to change colour from orange to yellow and towards green.

---
YT comments: he physical property exhibited in this experiment is known as fluorescence thermochromism. As demonstrated in the video, it is caused by a change in temperature. Typically LEDs work by exciting electrons up into a higher energy state, using an applied electric field. When an electron is initially excited, it can cause the molecule to vibrate, releasing energy. This energy is released as heat. The remaining energy in the electron is then converted to light, as a photon is released.

However, if the substance is cooled by liquid nitrogen, the initial energy loss from molecule vibrating is reduced (heat is caused by molecular vibrations). This means that there is now more energy that can be converted to light energy, instead of molecular vibrations. This causes the color change because green light has higher energy than orange light. The energy change is small, a difference of 2.051 electon volts for orange light to 2.192 electron volts for green light, but it is noticeable.